You won't find a good dependable skimmer for under $100 that is not a Seaclone or skilter. The only skimmers in that price range are air stone driven and don't match even come close to matching the quality of the venturi designed skimmers.
If you want a good skimmer at a not so bad price (~$130), get a Pak Pak 2. This is a HOB
If you want a really great skimmer for a little more (~$160) Get an Aqua C. Again this is a HOB
Both of these skimmers also come in a design that allows them to be placed in the sump.